1. Field of the Invention
The present invention relates to a method for preparing diamond or diamond-like carbon by using a combustion flame. The diamond or diamond-like carbon is useful as grinding material to form a flat surface or as abrasion resistant materials.
2. Discussion of Background
Heretofore, the following methods are known for the preparation of diamond by vapor phase synthesis which does not require a high temperature or high pressure.
(1) A so-called ion beam vapor deposition or ion plating method wherein carbon ions or hydrocarbon ions are formed by electric discharge, and they are accelerated by potential gradient to impinge on a substrate to precipitate diamond thereon.
(2) A so-called plasma method, heated tungsten filament method, photo-CVD method, high frequency heat plasma method or direct current arc method, wherein a gas mixture of a hydrocarbon and hydrogen is activated by means of a plasma, heat or light to precipitate diamond on the surface of a substrate.
However, with such methods except for the high frequency heat plasma method and the direct current arc method, the diamond-forming rate is as low as from 0.1 to 1 .mu.m/hr, and the area for precipitation of diamond is small. Besides, the apparatus are very expensive. Whereas, the high frequency heat plasma method and the direct current arc method have a drawback that the apparatus are extremely expensive, although the diamond-forming rate is high at a level of a few .mu.m/min.